The answer to this would be yes and no and this is why. If your opener was manufactured before 1990 then it most likely will have dip switch technology or early radio frequency technology both a very easy to copy the dip switch is the easiest to copy because it is visual you have to turn a series of 8 to 12 switches on or off and the combination in which you set the switches is what sets your code and if anybody wanted to get your code they would just have to look if the switches are on or off and copy them or write them down on a piece of paper and they would automatically have your code.
All they would have to do is go to any store by a dip switch compatible opener remote put your code in and easily brake in your house. When manufacturers stopped with the dip switch technology, they started using radio frequency signals. this worked very well for a while . until technology figured out a way to capture radio frequency signals with a device that does exactly that.
So now you have a way for somebody with the correct device to do so sit in a car across the street from your home and when you press the remote button in your car they now have captured your frequency signal to open the garage door and then the same device all they have to do is push a button and then it will take that same signal and return it to the opener. And this is how they could enter you home through the garage. Now all the garage door opener manufacturers use, what they call a revolving code technology,
Liftmaster’s is called security plus and Genie Corporation calls there’s multicode 1 and multicode 2. This technology is a frequency based technology but now is digital like your wireless home phone and cell phones but the difference is it sends a different frequency code every time you press the open button on your remote. They use over 1 million different codes and then revolve all of them so if somebody is trying to copy your frequency then they cannot reuse it again because the opener knows it has already received that code and cannot be used a second time. As far as I know they have not created a device that can copy a revolving code remote for a garage door opener.
The only way that I can think of that somebody can copy your revolving code is to actually have their their own compatible remote to your opener unit and they would have to have access to your garage door opener and all they would have to do is push the learn button and programs their personal remote to your garage door opener. The only way to protect yourself from the situation is to wipe all the codes from the unit if you feel that someone in your home from outside your friends and family like a service technician. The chances of this actually happening are slim because most service technicians have to go through a criminal background screen.
